The long term aims of the parent grant (A1 31268) are: a) To determine the generality of antibody-medicated catalysis; b) To define the role of antibody catalysis in autoimmunity and immunological defense; c) to identify natural antigens capable of eliciting catalytic antibody formation; d) To determine the structural features of antibodies underlying their binding and hydrolytic activities; and, e) To isolate catalytic antibodies with potential therapeutic or investigative utility by screening of the immune repertoire. The specific aims of this FIRCA collaborative proposal are: 1. To evaluate the potential role of catalytic anti-DNA and anti-VIP antibodies in systemic lupus erythematosus (SLE) and asthma, respectively, by measuring: (i) the frequency of hydrolytic anti-DNA antibodies and anti- VIP antibodies in patients expressing these disorders and control healthy subjects, and (ii) the kinetics and specificity of DNA hydrolysis by these antibodies; 2. To determine the contribution of antibody subunits in DNA hydrolysis and binding. The experimental design is: a) Antibody purification from blood of healthy individuals, asthma patients and SLE patients; b) Preparation of radioactive DNA and VIP probes; c) Radioassay of DNA binding and hydrolysis by antibodies; d) Comparison of these activities in healthy and disease groups; e) Characterization of antibody kinetic properties and specificity using denatured DNA, native DNA and short oligonucleotides of defined length and sequence; f) Purification of antibody Fab fragments and light chains; g) Comparison of the Km, turnover number and specificity of intact antibodies and isolated antibody subunits.